Table 4. Selected Results for a Simple Practical Synthesis of a Variety of Benzimidazole Derivatives Using Azide–Isocyanide Coupling Catalyzed by a Phenothiazine-Derived Mesoionic Singlet Carbene Palladium (4) Complex^a,b.

^aReaction conditions: azide (0.369 mmol), isocyanide (0.443 mmol), complex 4 (0.003 mmol, 1 mol %), and K₂CO₃ (1.10 mmol) in 5.0 mL of toluene at 50 °C for 12 h. Reaction mixture was cooled to room temperature and then CuI (0.100 mmol, 10 mol %), 1,10-phenanthroline (0.200 mmol, 20 mol %), Cs₂CO₃ (2.00 mmol), and N-heterocycle (1.10 mmol) were added to it and heated at 80 °C for 20 h.

^bIsolated yields (%).